Snow Part 07: Ingestive Precleaners: Tangential Air Filter Housing

Tangential Air Filter Housings pull snow into the filter housing. Frozen dump valves cannot seal properly and particle separation efficiency is lost. Saturated air filters can quickly blind over when frozen, starving the engine of air.

How the Tangential Filter Housing works to separate debris from the airflow:

  • The airflow is compressed at the point of entry, creating restriction, which causes the air entering into the filter housing to accelerate.
  • The air entry pipe is tangentially mounted on the air filter canister (on the side of the canister) which directs the accelerated air in a circular motion around the air filter.
  • This circular motion creates a centrifugal force which throws the heavier-than-air particles against the wall of the air filter housing.
  • The debris then slides down the wall to the bottom of the filter housing.
  • Some of the debris may make it as far as the dump valve, but other debris collects in the bottom of the filter house and is not evacuated.

How the Dump Valve works to release collected debris:

  • The dump valve is sucked shut while the engine is running, keeping the accumulated dirt inside of the filter housing.
  • Once the engine is shut off the vacuum is released.
  • The valve lips flap open.
  • The dirt that has collected in the tube above the dump valve is dropped onto the ground or into the engine compartment (depending on where the air filter housing is mounted).
  • Much of the debris may accumulate in the filter housing that never reaches the dump valve.

Both the standard air filter housing without a dump valve and the tangential air filter housing with a dump valve have proven only nominally effective in real-world environments. Lab data is collected under perfect conditions. Unfortunately, real weather greatly affects the ability of these systems to work as designed. Humidity, particle size, engine run time and the condition of the elastic dump valve all play a major role in its ability to dump the dirt back into the environment or engine compartment.

How does snow affect these two ingestive systems? In both cases, the snow is brought into the air filter housing. Dry snow is drawn onto the filter because it does not have enough mass to remain stationary on the bottom of the filter housing. The rapidly moving air flow picks up the snow which is literally flying around in the filter canister and sucks it onto the filter. Engine heat causes the snow to melt and soaks the filter. Once the filter is wet it is prone to freeze, preventing air from flowing through it and starving the engine.

Valve dumping onto EngineTangential filter housings with elastic dump valves are particularly vulnerable in sub-zero conditions. The dump valves lose their elasticity in very cold weather. When they freeze they can be easily broken or shattered. If the dump valve will not close while the engine is running the snow-laden air will enter through the dump valve and be pulled directly onto the filter. When this happens the filter becomes saturated very quickly. This particular problem exists for any system which relies upon rubber or elastic components to work in very cold weather.

The standard Air Filter Housing without a dump valve will draw the snow onto the filter at a slower rate but the results are the same. The machine will have to be shut down and the filter changed on a frequent and regular basis in order for the machine to continue to run properly or at all.

The Series 9000 has no rubber or elastic parts that can break or shatter in extreme cold.

Next: Part 8–Tube Body/Dona Cone

Previous: Part 6–Ingestive Precleaners

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